Horse Guards Parade & the Admiralty Citadel

The Admiralty Citadel on Horse Guards Parade in London is a bomb-proof World War II naval operations center featuring a twenty-foot-thick concrete roof and concealed gun loops for fortress defense. Constructed in 1939 with foundations thirty feet deep, the fortress housed 700 wartime staff across 156 rooms. Its rooftop lawn, designed to camouflage the structure from enemy aircraft, still requires mowing twice a year by hauling a lawnmower through an Admiralty office window.

London Β· from the walk β€œSecrets of Westminster & MI6” Β· audio ~4 min Β· Generated

Horse Guards Parade, London SW1A 2AX

What was the original purpose of the Admiralty Citadel on Horse Guards Parade in London?

Welcome to Horse Guards Parade... one of the most storied patches of ground in all of London. Right where you're standing, Henry the Eighth once watched knights clash in jousting tournaments. This was the tiltyard of the Palace of Whitehall, where tournaments were held in Tudor times. Centuries of ceremony have unfolded on this gravel... but today, I want you to turn away from the grand Horse Guards building and look toward that strange, vine-covered block squatting at the north end of the parade ground.......... That... is the Admiralty Citadel. And it is hiding in plain sight.......... Built in nineteen thirty-nine by the Ministry of Works, with architect W. A. Forsyth as consultant, it was designed as a bomb-proof operations centre for the Royal Navy, with foundations thirty feet deep and a twenty-foot thick concrete roof. Inside... one hundred and fifty-six rooms. Staffed around the clock by seven hundred people during the war. Their mission? Great dynamos stood ready to power the Admiralty's radio, by which any ship on the high seas of the world could be contacted. Every twenty-four hours, eight thousand messages went out through the Admiralty's signals communication branch.......... But here's what makes this place truly extraordinary. In the event of a German invasion, the building was intended to become a fortress, with loopholed firing positions provided to fend off attackers. Can you see them? Look closely at the walls... those narrow slits are gun loops. The Citadel would have been the last redoubt if German tanks ever rolled down The Mall.......... Now, Churchill himself famously called it a "vast monstrosity which weighs upon the Horse Guards Parade." After the war, its future was debated in Parliament in nineteen fifty-five, where Mps called it hideous and an offence to the architecture of London. Suggestions to improve it included cladding it in Portland stone, decorating it with statues of naval figures, or transforming it into the Hanging Gardens of London. None of it happened.......... And here is my Favorite detail. A lawn was planted on the roof to obscure the building from reconnaissance planes... and that grass Still needs mowing! Access is only possible from the second floor of the Admiralty, so twice a year, a lawn mower is pulled along the corridors, through an office and out of a window. Imagine being the civil servant whose carpet gets a trail of grass clippings twice a year!......... The Citadel is also linked by tunnels to government buildings all along Whitehall. In nineteen eighty, journalist Duncan Campbell managed to get into the tunnel network and described his exploration in the New Statesman. He found the network surprisingly easy to enter, with patrolmen more concerned about structural integrity than stopping intruders.......... The Admiralty Citadel still falls under the jurisdiction of the Ministry of Defence, and there is absolutely no public access. So take a good look... because the vine-covered wall in front of you is as close as anyone gets to one of London's most Secret buildings.

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